Oracle Linux 6 / 7 : openssl (ELSA-2015-1072) (Logjam)
Medium Nessus Plugin ID 84003
SynopsisThe remote Oracle Linux host is missing one or more security updates.
DescriptionFrom Red Hat Security Advisory 2015:1072 :
Updated openssl packages that fix one security issue are now available for Red Hat Enterprise Linux 6 and 7.
Red Hat Product Security has rated this update as having Moderate security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.
OpenSSL is a toolkit that implements the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols, as well as a full-strength, general purpose cryptography library.
A flaw was found in the way the TLS protocol composes the Diffie-Hellman (DH) key exchange. A man-in-the-middle attacker could use this flaw to force the use of weak 512 bit export-grade keys during the key exchange, allowing them do decrypt all traffic.
Note: This update forces the TLS/SSL client implementation in OpenSSL to reject DH key sizes below 768 bits, which prevents sessions to be downgraded to export-grade keys. Future updates may raise this limit to 1024 bits.
All openssl users are advised to upgrade to these updated packages, which contain a backported patch to correct this issue. For the update to take effect, all services linked to the OpenSSL library must be restarted, or the system rebooted.
SolutionUpdate the affected openssl packages.